1. Field of the Invention
This invention relates to an external operation device for electronic timepiece, particularly to a device in which a plurality of electric switches are integrated into a unit.
2. Description of the Prior Art
The electronic timepieces using a quartz crystal as a source of oscillation are rapidly progressing in recent several years. Particularly, the electronic timepieces of the type of liquid crystal display are offering displays of various functions that were impossible with the conventional mechanical timepieces, enabling the timepieces to find extensive applications.
The development of electronic timepieces of the type of liquid crystal display, however, has also resulted in the increase of the number of external operation devices that must be fitted to each of the electronic timepieces, presenting great burden to the job of the department in charge of the production of external members, to the job of the technical department and even to the job of the design department.
Push-button switches for electronic wrist watches must be simple in construction and small in size. According to the conventional switches, a resilient base plate is folded in a U-shape, electrodes are provided on the opposing surfaces of the base plate, and the resilient base plate is pressed by a push button so that the opposing electrodes come into pressed contact with each other thereby to close the switch. With the switches of such a type, however, the radius of curvature of a folded portion of the resilient base plate must be selected to be great to some extent in order for the folded portion to produce sufficient force or restoration, presenting such a defect that the stroke of the push button tends to be increased in a pushing direction.